1. Field of the Invention
The present invention relates to a fuel supply system that feeds fuel to an internal combustion engine.
2. Description of Related Art
A fuel supply system includes a fuel pump, a filter element, a pressure regulating valve, and a filter case. The filter element removes a foreign object in fuel discharged or pumped by the fuel pump. The pressure regulating valve adjusts pressure of the fuel that has passed through the filter element. The filter case receives the filter element. The fuel supply system limits noise, such as valve hit noise of the pressure regulating valve caused by pulse of fuel discharged from the fuel pump and is known as a fuel pump module (see JP-A-2003-155963 corresponding to U.S. Pat. No. 6,789,529).
In JP-A-2003-155963, there is provided a pipe in an outflow chamber defined by a bottom portion of the filter case and an end portion of the filter element toward the bottom portion for providing connection between the outflow chamber and an inlet portion of the pressure regulating valve. The pipe has an inlet that is positioned in the outflow chamber apart from an inlet portion of the pressure regulating valve.
Thus, fuel, which is discharged to a position close to the inlet portion of the pressure regulating valve of the filter element, may still has to flow around to the inlet of the pipe that is positioned apart from the inlet portion of the pressure regulating valve. Then, the fuel flows through the pipe to flow into the pressure regulating valve. Due to the above configuration, pulse of fuel that flows out of the filter element is limited, and thereby noise, such as a valve hit noise of the pressure regulating valve, is limited from being generated.
For example, there has been known a small-sized fuel pump module, in which a filter element is configured to cover an outer periphery of the fuel pump and a filter case for receiving the filter element is configured to cover a radially inner wall and a radially outer wall of the filter element (see JP-A-2004-68679 corresponding to U.S. Pat. No. 7,306,715).
However, when a fuel pulse limiting pipe in JP-A-2003-155963 is applied to a filter case in JP-A-2004-68679, the following disadvantages may occur.
The filter element described in JP-A-2003-155963 has a cylindrical column shape. Because the filter case receives the above cylindrical filter element, the outflow chamber formed at the bottom portion of the filter case is also required to have a cylindrical column shape. In contrast, the filter element described in JP-A-2004-68679 has a hollow cylindrical shape. The filter case is configured to cover the radially inner wall and the radially outer wall of the filter element. As a result, the outflow chamber provided at the bottom portion of the filter case has a circular ring shape. As the filter case is further reduced in size, the outflow chamber has a shorter dimension in a radial direction.
As a result, it is considerably difficult to assemble a fuel pulse limiting pipe to the bottom portion of the filter case described in JP-A-2004-68679. Also, in a case, where the small filter case is further reduced in size, it becomes more difficult for an operator to put his or her hand into the bottom portion of the filter case, and thereby the operator is unable to assemble the pipe.